Blood and tumor tissue samples are collected at baseline for correlative laboratory biomarker and pharmacogenomic studies. Samples are analyzed for total c-Src and phosphorylated Src expression by IHC; polymorphisms and gene rearrangements/activating mutations in PDGFA (within exons 18 and 12) and KIT (within exons 9, 11, 13, and 27) by PCR; and additional biomarkers associated with Src signal transduction and/or dasatinib response (e.g., phospho-KIT, phospho-PDGFR, EPHA2, VEGF, Stat3, Bcl-x, survivin, cyclin D1, and p27_Kip) by IHC.